Heat resisting alloys

ABSTRACT

The invention concerns with highly improved heat resisting NiAl-Be alloys. The improvement resides in the selection of specific alloying ratios as determined by a certain specific polygonal area plotted on a triangular coordinate diagram of Ni, Al and Be, for general improvement of the high temperature antioxidation performance, high temperature strength and high temperature toughness of the alloys.

nited States Patent Komatsu et al.

HEAT RESISTING ALLOYS Inventors: Noboru Komatsu; Takatoshi Suzuki;

Takuo Ito, all of Nagoya, Japan Kabushiki Kaisha Toyota Chuo Kenkyusho,Aichi-ken, Japan Filed: July 29, 1970 Appl. No.: 59,169

Assignee:

Foreign Application Priority Data Aug 2, 1969 Japan r v n45l6l344 May 8,l970 Japan ..45/39463 US. Cl ..75/l70, 75/122, 75/134 N,

75/134 F, 148/32 Int. Cl ..C22c 19/00 Field of Search ..75/l70, 171,150, l38, 122, 75/134 N, 134 F; 148/32, 32.5

51 Feb. 6, 1973 [56] References Cited UNITED STATES PATENTS l,685,5709/1928 Masing et al. ..75/l70 2,157,979 5/1939 Cooper ct al ..75/l502,193,363 3/1940 Adamoli ..75/l50 Primary Examiner-Richard 0. DeanAtt0rneySughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT Theinvention concerns with highly improved heat resisting Ni-Al-Be alloys.

The improvement resides in the selection of specific alloying ratios asdetermined by a certain specific polygonal area plotted on a triangularcoordinate diagram of Ni, Al and Be, for general improvement of the hightemperature antioxidation performance, high temperature strength andhigh temperature toughness of the alloys.

4 Claims, 6 Drawing Figures P'ATENTEDFEB ems 3,715,206

SHEET 1 [IF 3 FIG. I

AM/W 6 .51 AAAMWA 9,

O Ola Ni I0 2630 so o so Al,Gt./o

PATENTEDFEB 6 I975 SHEET 2 OF 3 Al, CLO/0 0 O m 5 $89 1 mmmzom MEASURINGTEMPERATURE C PATENTEDFEB 6 1975 3,715,206

NW IO W M Ni Al IO 20 3O 4O 5O 60 Al. OT. /0

HEAT RESISTING ALLOYS This invention concerns highly improved heatresisting alloys representing superior antioxydation properties even athigher temperatures, as well as superior high temperature strength andtoughness properties.

With modern rapidly developing and expanding technology and industrialmanufacture, demands of high temperature heat resisting materials,especially durable to substantially higher temperatures than 1,000C areamazingly increasing. These exceptionally superior heat resistingmaterials are now demanded for use in the manufacture of rocket shells;atomic heat engine parts; fuel combustion chambers and jet organs ofjet-propulsion engines; blades or the like parts of gas turbines; hightemperature and high pressure equipments in chemical plants; hightemperature valves and the like. These parts and equipments are exposedto very high temperatures and severe loads.

Although until nowadays various and profound studies and investigationshave been made for the realization of the heat resistant materials, thefollowing limitation must be imposed in the use of these materials. Asan example, the heat resistant steel must be used in practice at atemperature range lower than 800C. Heat resistant alloys containing asits main constituent Ni or C0, the practically usable temperature rangewill increase to about 1,000C. With higher temperatures than 1,000C,these heat resistant alloys represent generally a substantially reducedstrength, as well as abruptly decreased antioxidation properties whichtendency prevents these alloys from their prolonged usage.

On the other hand, fire resistant alloys containing Mo, Nb and Ta, andceramic materials can be used at higher temperatures than 1,000C for along time. These fire resistant alloys, however, show an inferiorantioxidation performance at high temperatures so that the kind, natureand working conditions of the environmental atmosphere are limitativeand/or a certain surface treatment for intensifying the antioxidationperformance must preferably be applied. 1n the case of ceramicmaterials, considerable drawbacks will be encountered by the lack ofductility, malleability and shock resistibility, resulting in aliability to destruction when subjected to a sudden and substantialtemperature change. lt may therefore be definitely concluded thatconventional heat resistant materials when used in various hightemperature parts and equipments represent much to be desired and mustbe further improved.

lt is the main object of the invention to provide such heat resistantalloys as capable of obviating substantially the aforementionedconventional drawbacks.

It is a further object of the invention to provide heat resistant alloyshaving superior antioxidation performance, mechanical strength andtoughness even in a high temperature range between about l,000 and about1,200C.

1n the progress of our investigation into the development of heatresistant alloys capable of satisfying the above mentioned objects,attention has been directed at first to Ni-Al alloys and Ni Al alloyswhich means intermetallic compounds as will be referred to hereinafterthroughout the present specification, having superior high temperatureantioxidation properties. Our investigation has been further directed toimprove the high temperature hardness and toughness of the above kind ofheat resisting alloys, and, indeed, without inviting any reduction oftheir superior antioxidation properties.

From the results of a larger number of practical experiments carried outin the above sense, we have found that the ternary Ni-Al-Be alloys whichcan be produced by adding Be to the binary Ni Al alloys of the abovekind and comprise specific alloying ratios lying within an imaginarypoligonal areas as determined by specific five apexes drawn on thetriangular coordinate chart of said three alloying components: Ni, Aland Be. The first apex is fixed by a specific alloying ratio of Ni 48at. Al 0.1 at. and Be 51.9 at. this first apex being referred to asl-point" hereinafter throughout the specification. The second apex isfixed by a specific ratio of these three alloying components: Ni 50.1at. Al 0.1 at. and Be 49.8 at. this second apex being referred to as.l-point" hereinafter. The third apex called K-point" is fixed by aspecific ratio of these alloying components: Ni 61 at. Al 1 1 at. and Be28 at. 1n the similar way, the fourth apex called B- point" isdetermined by an alloying ratio: Ni 87 at. Al 11 at. and Be 2 at. Thefifth apex called C- point is determined by an alloying ratio: Ni 48 at.A at. and Be 2 at.

These alloys will be called hereinafter throughout the specification asthe first range alloys. The at.% is meant by atomic percentage which maybe abbreviated hereinafter only to When the hardness of the alloy shouldbe evaluated at most, it can be selected from a polygonal area in saidtriangular co-ordinate chart covered by six apexes of 1, J, K, D, E andC-points. The points 1, .l, K and C are same as before, while theD-point is fixed by an alloying ratio of: Ni 79% Al 1 1% and Be 10% andthe 15-point by a ratio of: Ni 71%; Al 27% and Be 2%. These alloys willbe referred hereinafter as the second range alloys."

When the antioxidation performance, the hardness and the toughness ofthe alloy must be evaluated jointly at the most, it can be selected froma polygonal area in said triangular coordinate chart covered, however,by six apexes of F, G, D, E, C and H, of which the three D, E- andC-points are same as before, while the F- point is determined by aspecific alloying ratio: Ni 51%; Al 14% and Be 35%; the 6-point by: Ni69%; Al 11% and Be 20%; and the H-point by: Ni 48%; Al 39% and Be 13%,as will be more fully described hereinafter. These alloys will bereferred to as the third range alloys throughout the specification.

Further, when the relative strength of the alloy should be highlyevaluated, it can be selected from a polygonal area in said triangularcoordinate chart covered, however, by four apexes of A-, l-, J and 1(-points, of which the first or A-point is determined by a specificalloying ratio: Ni 48%; Al 11% and Be 41%, while the remaining threepoints 1, J and K are same as before. These alloys will be referred tohereinafter throughout the specification as the fourth range alloys."

These and further objects, features and advantages of the invention willbecome more apparent when read the following detailed description of theinvention by reference to the accompanying drawings illustrative ofseveral preferred embodiments thereof shown only by way of examples.

In the drawings:

FIG. 1 is a Ni-Al-Be triangular coordinate diagram showing a pluralityof test specimen alloys used in the experiments carried out on heatresistant Ni-AlBe als.

FIG. 2 is a Ni-AlBe triangular coordinate diagram showing severaldifferent areas of oxidation weight increase of Ni-Al-Be alloyesappearing on the said diagram.

FIG. 3 is a Ni-Al-Be triangular coordinate diagram showing severaldifferent areas of room temperature hardness of Ni-Al-Be alloysappearing on the said diagram.

FIG. 4 is a chart of the harness of various alloying materials used forthe preparation of the heat resistant Ni-Al-Be alloy according to theinvention, being plotted against measured temperature.

FIG. 5 is a Ni-AlBe triangular coordinate diagram showing severaldifferent areas of toughness of Ni-Al-Be alloys appearing on the saiddiagram.

FIG. 6 is a NiAl-Be triangular coordinate diagram showing severaldifferent composition ranges of the heat resisting alloys proposed bythe present invention.

All the triangular coordinate diagrams shown are prepared in the form ofregular triangles. All the sides of each of these triangular diagramshave corresponding scales of the arithmetical order.

' As seen, the left-hand and right-hand sides represent the nickelcontent and the beryllium content, respectively, while the bottom siderepresents the aluminum content.

In the experimental preparation of the Ni-Al-Be heat resistant alloysaccording to this invention, the alloying materials were electrolyticnickel, high purity aluminum, metallic beryllium, Ni-Be alloy and Al-Bealloy. These materials were melted together by a specifically selectedmelting process to be described below and then moulded into sampleswhich were subjected to tests.

On account of large affinity of beryllium with oxygen, the alloyingmaterials were melted in a specific vessel relying upon the floatationprinciple, in order to avoid the formation of oxidation impurities.

As the melting atmosphere, argon was used after addition of a smallquantity of hydrogen, for avoiding otherwise encountered oxydation. Themolten alloy was cast into a copper moulds.

For the determination of the inventive alloying range, we have preparedabout 80 kinds of the ternary alloys comprising Ni, Al and Be, of whichseveral representatives are shown in FIG. 1. The nature of thistriangular coordinate diagram is quite obvious from the foregoingdisclosure by any person skilled in the art. As an example, a specificpoint shown at Y" represents an alloy consisting of Ni 30%; Al 40% andBe 30%. The test specimens shown have respective nickel contentshigherthan about 30%; aluminum contents lower than about 65 andberyllium contents lower than about 50%. Specimens having other alloyingratios have been omitted from the drawing, since it has beenacknowledged by experiments that these outsiders do not represent thedisired effects.

By use of these specimens, the antioxidation performance wasinvestigated.

In this case, the specimen of 8 mm 41, 5 mm long was measured byweighing it on a chemical balance in units of 0.01 mg. Then, thespecimen is put on a ceramic boat made of alumina and kept at 1,200C for5 hours in an electric furnace, and cooled down in open air atmosphere.The specimen was weighed again and the weight increase was determined.These values were expressed in terms of weight increase, mg, divided bythe surface area of the specimen, cm and classified into four categoriesas shown in the following Table l. The results are also showngraphically in FIG. 2, as attached respectively with l, m, n and 0.

Table 1 Ranges of Oxydation Weight Symbols Increase (mg/cm) expressed inFIG. 2

less than 0.49 1" 0.50 to 0.99 m higher than 1.0 "n" melted at 1,200C."0"

The practical values of oxidation weight increase of those alloys havinga ratio: Be about 30 53%; Ni about 45 60% and lying in the range area ofn in For comparison, the conventional heat resisting alloy NEMONIK wastested simultaneously, showing an oxidation weight increase of 3 mglcmWith increase of the oxydation weight increase value, the antioxydationproperty of the alloy will naturally become inferior. It is thereforedefinitely seen that the Ni-Al-Be alloy according to this invention hassubstantially superior antioxidation performance over conventional heatresisting alloys.

In FIG. 2, a Ni A1 alloy having a ratio of: Ni 50% and Al 50%, and a NiAl alloy having a ratio of: Ni and A1 25%, are also shown. Theseconventional alloys are also plotted on other triangular coordinatediagrams shown and to be described.

Next, the room temperature hardness tests were performed with the testspecimens of the inventive alloy on a Vickers hardness tester with aload of 5 kg. The thus measured values, I-Iv, are grouped into fiveranges according to the schedule shown in the following Table 3. Thesame results are graphically shown in FIG. 3.

Table 3 Corresponding Range of Hardness, Hv Symbols shown in FIG. 3

In consideration of the similar tests on the conventional alloys Ni Al(I-IV: 330) and Ni Al (Hv: 220), the superior effect obtained by theaddition of beryllium will be obvious from the foregoing.

Next, the relationship of the inventive alloys between the hardness andthe temperature was experimentally investigated, partially based uponthe foregoing hardness tests.

For this purpose, nine kinds of specimens Kl K7, K Kll shown in thefollowing Table 4 were selected out from the four room temperaturehardness ranges q, r, s" and t. These samples are also plotted on thediagram in FIG. 3 as attached with same specimen symbols.

In the progress of the experiments, the specimen was heated up to 1,200Cand the hardness was measured at each temperature increase increment of100C on a Vickers micro-hardness tester loaded with 300 grs.

The test results are plotted on the chart shown in FIG. 4 which has beenprepared with a logarithmic hardness scale, l-lv, and an arthmetictemperature scale, C, as shown.

For comparison, a specimen, K of conventional heat resisting steelSUH31B (JIS Japanese Industrial Standards) and a further specimen,Specimen K Haynes Stellite Superalloy H825 of cobalt base, the bothalloys being highly well known in Japan as of superior high temperaturehardness, were simultaneously tested and the results are also shown inFIG. 4.

Table 4 Specimen Composition, at.

It will be clearly observed from FIG. 4, those which have been preparedby adding beryllium to Ni-Al alloys and having a superior roomtemperature hardness over Hv: 400, represent more improved hightemperature hardness than that of the basic binary alloys, the novelalloy keeping its room temperature hardness until about 700C. The novelalloys when they have Hvvalues 750-850 at room temperature, they cankeep these values until about 900C. Therefore, the addition of berylliumprovides a substantial technical advantage also in the above sense atsubstantial high temperatures, as ascertained from the test results ofspecimens K4 and K5.

When comparing with the hardness of conventional heat resisting steeland -alloy, Specimens-K8 and -K9, the novel Ni-Al-Be alloys K2 K7 andK10 K1 1, represent three to five times higher values of roomtemperature hardness.

When considering the fact that the conventional alloys asrepresentatively expressed by Specimens K and K show a rather inferiormaximum allowable temperature of 800 900C for keeping its hardness Hv:100. In the case of the novel ternary alloys, even when consideringthose representing rather appreciable hardness variation in function oftemperature variation, such as in the case of the Specimens K and K themaximum allowable temperature amounts to higher than 900C forrepresenting the hardness lower than Hv 100. In the case of theSpecimens K and K-,, the critical temperature value amounts to as highas 1,000 1,100C.

In the case of the still improved alloys having a higher percentage ofberyllium content, such as Specimens K and K and the hard Specimens Kand K having room temperature hardness Hv: 750 850, can represent I-Iveven at 1,200C. It can be thus concluded that the improved alloysaccording to this invention, when having a superior room temperaturehardness in the order of Hv 400 or higher, can show I-lv 100 even at900C which performance is substantially superior over the comparativeconventional heat resisting alloys.

Those of novel alloys which have over HV 600 or a higher berylliumcontent represent not only superior room temperature hardness, but alsosubstantially improved high temperature hardness over the conventionalalloys.

Our investigation was continued on the problem of the toughness. Forthis purpose, test experiments were carried out in the conventional wayas frequently adopted for the determination of the toughness of thecemented hard alloys. More specifically, the specimen was impressed on aVickers hardness tester and the critical load was measured when cracksappeared around the formed impression. When the critical load issmaller, the stock is naturally of lesser toughness.

In a number of experimental tests of the novel Ni-Al-Be alloys, theimpressing load applied on to the specimen was varied successively from1 through 5, I0, 20 and 30 to 50 kgs., and at each specific loadapplication, three impressions were formed on the specimen so as to wellinvestigate possible development of cracks around each of theimpressions. When cracks should be found around even one of theseimpressions, the degree of toughness of the alloy was determined interms of the load, X kgs. implied at that time.

The thus measured results were classified into successive five ranges asappearing in the following Table 5. These classified ranges aregraphically shown on the triangular coordinate diagram shown in FIG. 5.

Table Classified Ranges of Corresponding Symbols Applied Loads, X inkgs. Shown in FIG. 5

Higher than 50 i 14" In the first line of Table 5, the expression higherthan 50 means that no cracks were observed around each of threeimpressions formed under the impression load of 50 kgs.

As will be observed from FIG. 5, the toughness increases generally withdecrease of aluminum content. It will be further observed from thediagram that the addition of beryllium to the corresponding binary Ni-Alalloys can provide a substantial improvement in the toughness of thealloy.

As the alloying material for supplying Ni-, Aland Becomponent,electrolytic nickel, high purity aluminum, metallic beryllium,nickel-beryllium alloy and aluminum beryllum alloy were used, which may,however, include small amounts of Fe, Si, Cu, Co and the likeimpurities. In the above experiments, these impurities amount only to0.2 0.4 percent in total. Thus, these material contained practically nocontents of impurities. It should be, however, noted that the use ofsuch high purity alloying materials was made only for best control ofthe alloy components which does not means that an inclusion ofimpurities gives always rise to the formation of inferior heat resistingalloys.

In the following, the technical reasons for adopting the specificallyselected alloying range as was defined hereinbefore will be describedhereinbelow more in detail.

For the selection of the limited and specific alloying ratios for thefirst range alloys, the hardness, the toughness and the oxidation weightincrease less than 2.0 mg/sq. cm were considered in combination.

As for the nickel content, it was observed a melting of the alloy inproximity of 1,200C with the nickel content less than 45 percent. Inthis case, the toughness and hardness were found inferior. The meltingphenomenon was observed in the range o." When considering the lowerlimit of nickel content from these consideration, the limit shouldpreferably placed at the border line between m and n range areas.

From this reason, the lower limit of nickel content was selected to 48percent which is defined by the line C-I shown in FIG. 6, said linepasses through the 1'!- point as defined by the ratio: Ni 48%; AI 39%and Be 13%. Throughout the both ranges m, and n, the most apparentinferior antioxidation performance of the alloy having been observed atthis point H, as may be well observed from FIG. 2.

As for the aluminum content, a melting phenomenon was observed at atemperature in proximity of about 1,200C when the Al-content wasselected to less than 9 percent with the nickel content amounted to overabout 61 percent. It was observed that throughout the combined overallarea covering 1-, n and 0"- ranges the most inferiority of antioxidationwas observed at G-point shown in FIG. 2 which was defined by the alloyratio of: Ni 69%; Al 11% and Be 20%, as was referred to hereinbefore.Therefore, with the nickel content higher than about 61 percent, thelower limit of aluminum content was selected to 11 percent whichcorresponds to the line B-K in FIG.6.

With the nickel content less than about 61 percent and with a highercontent of beryllium, the range of the oxidation weight increase set toless than 2.0 mg/sq. cm lies rightwards from a specific point a inF1G.2, as may be well supposed from the tests on Specimens n, n,,, therightward area relative to n representing more high aluminum contents ofthe inventive alloys. From this reason, the lower limiting border forattaining the oxidation weight increase set to less than 2.0 mg/sq. cmwith the nickel content less than about 61 percent was fixed by thelimiting line J-K shown in FIG. 6. The line J-K is defined by the twopoints of Ni 50% and Be 50%; and Ni and Al 25%. Point J and K aredefined by the specific alloying ratios of Ni 50.1%, A1 0.1% and Be49.8%, and Ni 61.0%, A1 11.0% and Be 28.0%, respectively.

As for the beryllium content, addition of a small quantity of Be canimprove the aforementioned performance. When considering, however,mainly the toughness, this property will become inferior with suchalloying ratio as of Ni 64-72%; Al 2836% and Be less than 2% which rangeis shown by the area Y in FIG. 5, over that of the conventional Ni Alalloys which are represented by the aforementioned area X. Uponconsidering these facts, the lower limit of Be was set to 2 percent, asbeing expressed by the straight line B-C in FIG.6.

With the range of substantially higher content of Be, it was found thatthe desired purpose can only be attained with the aluminum contenthigher than 0.1 percent. From this reason, the lowest limit of Al wasset to 0.1 percent, as represented by the straight line I-J in FIG. 6.

From the above various considerations for attaining satisfactorysuperior performances of toughness and normal and high temperaturehardness and, indeed, with the oxidation weight increase set to lessthan 2.0 mg/sq. cm, the overall alloying range was limited by thoselying within the polygonal area defined by the specific points C, I, J,K and B in FIG. 6. These points correspond to specifically selectedalloying ratios, as was described hereinbefore.

These alloys called the first range alloys, as was referred tohereinbefore, represent similar or somewhat inferior antioxidationperformance in comparison with that of Ni Al or Ni Al alloys which areknown to have the most efficient antioxidation performance. These novelalloys, however, represent highly superior hardness and toughnessproperties in combination. When, therefore, reviewing the overallperformance regarding said three kinds of desirous properties, thesenovel alloys have a preferential performance over the conventional heatresisting alloys and can find their way of utilization as the highpressure, high temperature, high load, and thus highly valuable materialin the manufacture of steam and gas turbines, jet propulsion engines,rockets, chemical plant facilities and/or the like.

Next, referring to the second range alloys, it will be easily observedfrom the foregoing disclosure that the higher nickel content alloysincluded in q-range in FIG. 3, represent normal temperature hardnessless than Hv 399, and somewhat inferior high temperature hardness. When,therefore, deleting these alloys from the aforementioned overallalloying range suggested by the novel teaching of the invention, theremaining alloys represent superior room temperature hardness higherthan I-Iv 100. Therefore, these alloys can be effectively utilized asthe high temperature hardness material for use in the manufacture ofcutting tools, turbine blades, -disks and the like parts which must behighly of the heat resisting nature. These alloys corresponds to thesecond range alloys defined above. In this case, the range areaIJK-DE-C-I includes all the second range alloys. The point D was fixedby the intersection point between the curved line connecting a firstpoint corresponding the alloying ratio of Ni 79% and Be 21% to a secondpoint corresponding to Ni 68% and Al 32% in FIG. 3, representing theroom temperature hardness of I-Iv 400, and the straight line connectingthe two points K and B. The points E was fixed by the intersection pointof the said first curved line with the third straight line connectingtwo points B and C, instead of the above points K and B in theforegoing. The selection of these points can be easily understood byobserving FIG. 3 in combination with FIG. 6.

The q-range area in FIG. 3 showing the alloy ratios of: Ni 48-58%; Al42-52% and Be smaller amounts, representing the hardness less than Hv399, defines such alloys having a maximum beryllium content of about 1.8percent and thus being deleted from inclusion within the second rangealloy group.

Next, the third range alloys will be described more in detail.

When the novel alloys belonging to the first range are used as thematerial in the manufacture of such highly heat resisting parts anddevices as gas turbine nozzles, combustion chamber material of that kindof turbine, suction and discharge or exhaust gas valves of automotivedrive engine, various high pressure and high temperature parts ofchemical and/or industrial plants, blades of jet propulsion engines,they must represent superior antioxidation performance, hardness andtoughness in combination. In this case, the oxydation weight increaseshould preferably be less than 1.0 mg/sq. cm. The room temperaturehardness must preferably be higher than H 400 from the same reason asthat referred to hereinabove in connection with the second range alloys.

The toughness should be higher than that of the conventional Ni-Alalloy.

In order to satisfy these various and more severe operating conditions,it is recommendable to utilize the third range alloys according to thisinvention.

For satisfying the superior toughness as required above and over that ofconventional Ni-Al alloys, and the hardness requirement of higher thanH,,399, the second range alloys could be utilized to a satisfyingdegree.

It will be observed from the foregoing, however, that these alloys cannot satisfy the required antioxidation performance, should the alloyscontain more abundant content of beryllium, thereby representing ahigher rate of oxidation weight increase such as 1.0 mg/sq. cm. Fromthis reason, those alloys which belong to n range area have been removedfrom the second range alloys and only those alloys covered by a stillreduced polygonal area defined by several specific points F, G, D, E, Cand H are recommended to use for the above purpose. F-point is definedin the range I by selecting a specific alloying ratio of: Ni 51%, Al 14%and Be 35%, as was referred hereinbefore, which corresponds to themaximum beryllium content in this range I. The discarded alloy range isdefined thus by a polygonal area having its apexes constituted byseveral specific alloying ratio points F, H, I, J, K and G.

When the novel Ni-Al-Be alloys should be used for the manufacture ofsuch machine parts as of turbine blades, aircraft and rocket shells andthe like which require a high relative strength, those alloys having ahigh beryllium content should preferably be selected. For satisfyingthese requirement, such alloys which are covered by the still reducedpolygonal area A-I-J-K-A can advantageously be used. The A-point isdefined as an intersecting point of an extension of the straight line.B-K with the line C-I. These alloys are defined as the fourth rangealloys, as was referred to hereinbefore. The density of these alloysamounts to about 5.8 6.8 g/cub. cm which is substantially lower thanthese of the conventional heat resisting steel and alloy amountinggenerally to 8 9 g/cub. cm. The high temperature hardness and toughnessare higher thanconventional, thus providing higher value of relativestrength.

We have investigated further by carrying out a plu rality of experimentsand found that less than half of the nickel content may be replaced byFe or C0, so far as the contents of Be and Al are reserved as before. Inthis case, the hardness value can be increased, while the antioxidationperformance and the toughness of the alloy are somewhat reduced. Asample of these quaternary alloys may be: Ni 25%; Co 25%; Al 38%, Be12%. In comparison with Hv 550 of room temperature hardness of theternary alloy, the quaternary alloy represents, by way of example, Hv700. C0 can be replaced by the corresponding amount of Fe. The natureand behavior of these are substantially same as those of the Co-replacedalloys.

The novel Ni-Al-Be alloys according to this invention do not mean in anyway the pure ternary alloys which may, however, contain a small mount ofimpurities, so far as they do not affect upon the desired effectsadversely to a detrimental degree. The novel alloy may include, amongothers, a small amount of impurities such as Fe, Si, Cu, Co and the likewhich are frequently included as impurities in the commercializedmetallic nickel, metallic aluminum, metallic beryllium, nickelberylliumalloy, aluminum-beryllium alloy, aluminumberyllium alloy.

According to our experiments, inclusion of these impurities, such as Feless than 1.0 wt. CuO less than 3.0 wt. and a trace of Co as frequentlycontained in commercial metallic nickel (Grade 3,.11S), Fe less than 1.5wt.%; Si less than 1.5 wt. and a trace of Cu as frequently containedfrequently in commercial metallic aluminum (Grade 4, HS), various smallamounts of Fe, Na, Cu and the like contained frequently in commercialmetallic beryllium, small amounts of Fe, Si, Cu and the like frequentlycontained in commercial aluminumberyllium alloy, and/or small amounts ofFe, Cu, Co and the like frequently contained in commercialnickelberyllium alloy do not affect adversely upon the desired andadvantageous properties of the novel ternary alloy according to thisinvention.

It will be seen from the foregoing that in the practice of theinvention, the alloying materials are not limited to those which havebeen demonstrated in the foregoing detailed description and commerciallyavailable alloying materials such as metallic nickel, metallic aluminum,metallic beryllium and alloys thereof can well be utilized within theframework of the invention.

in the foregoing detailed description, the percentages of the alloyingelements have been represented in atomic percentages, if not otherwisenoted.

In the following Table 6, the atomic percentages as found at the severalforegoing critical points A, B, C, D, E, F, G, H, I, J and K have beenshown in comparison with the corresponding wt. percentages of thealloying elements.

The embodiments of the invention in which an exclu- 51.9 at the secondone being defined by a second alloying ratio ofNi 50.1 at A 0.1 at andBe 49.8

at the third one being defined by a third alloying ratio of Ni 61 at Al11 at and Be 28 at.%, the

fourth one being defined by a fourth alloying ratio of Ni 87 at.%; Al 11at.% and Be 2 at.%, and the fifth one being defined by a fifth alloyingratio of Ni 48 at.%; Al 50 at.% and Be 2 at.%.

2. A heat resisting alloy consisting essentially of Ni, Al and Be,wherein the amounts thereof are defined by and included in a polygonalarea on a triangular coordinate diagram of Ni, Al and Be, the polygonhaving six apexes of which the first one being defined by a firstalloying ratio of Ni 48 at.%; A] 0.1 at.% and Be 51.9 at.%, the secondone being defined by a second alloying ratio of Ni 50.1 at.%; A1 0.1at.% and Be 49.8 at.%, the third one being defined by a third alloyingratio of Ni 61 at.%; Al 11 at.% and Be 28 at.%, the fourth one beingdefined by a fourth alloying ratio of Ni 79 at.%; Al 11 at.% and Be 10at.%; the fifth one being defined by a fifth alloying ratio of Ni 71at.%; Al 27 at.% and Be 2 at.% and the sixth one being defined by asixth alloying ratio of Ni 48 at.%; Al 50 at.% and Be 2 at.%.

3. A heat resisting alloy consisting essentially of Ni, Al and Be,wherein the amounts thereof are defined by and included in a polygonalarea on a triangular coordinate diagram of Ni, Aland Be, the polygonhaving six apexes of which the first one being defined by a first a1-loying ratio of M51 at.%; Al 14 at.%and Be 35 at.%; the second one beingdefined by a second alloying ratio of Ni 69 at.%; Al 11 at.% and Be 20at.%, the third one being defined by a third alloying ratio of Ni 79at.%; Al

11 at.% and Be 10 at.%, the fourth one being defined.

by a fourth alloying ratio of Ni 71 at.%; Al 27 at.% and Be 2 at.%, thefifth one being defined by a fifth alloying ratio of Ni 48 at.%; Al 50at.% and Be 2 at.% and sixth one being defined by a sixth alloying ratioof Ni 48 at.%; Al 39 at.% and Be 13 at.%.

4. A heat resisting alloy consisting essentially of Ni, Al and Be,wherein the amounts thereof are defined by and included in a polygonalarea on a triangular co-ordinate diagram of Ni, Al and Be, the polygonhaving four apexes of which the first one being defined by a firstalloying ratio of Ni 48 at.%; Al 11 at.% and Be 41 at.%, the second onebeing defined by a second alloying ratio of Ni 48 at.%; A1 0.1 at.% andBe 51.9 at.%, the third one being defined by a third alloying ratioof Ni50.1 at.%; A1 0.1 at.% and Be 49.8 at.% and the fourth one being definedby a fourth alloying ratio of Ni 61 at.%; Al 11 at.% and Be 28 at.%.

1. A heat resisting alloy consisting essentially of Ni, Al and Be,wherein the amounts thereof are defined by and included in a polygonalarea on a triangular coordinate diagram of Ni, Al and Be, the polygonhaving five apexes of which the first one being defined by a firstalloying ratio of Ni 48 at .%; Al 0.1 at .% and Be 51.9 at .%, thesecond one being defined by a second alloying ratio of Ni 50.1 at .%; Al0.1 at .% and Be 49.8 at .%, the third one being defined by a thirdalloying ratio of Ni 61 at .%; Al 11 at .% and Be 28 at.%, the fourthone being defined by a fourth alloying ratio of Ni 87 at.%; Al 11 at.%and Be 2 at.%, and the fifth one being defined by a fifth alloying ratioof Ni 48 at.%; Al 50 at.% and Be 2 at.%.
 2. A heat resisting alloyconsisting essentially of Ni, Al and Be, wherein the amounts thereof aredefined by and included in a polygonal area on a triangular coordinatediagram of Ni, Al and Be, the polygon having six apexes of which thefirst one being defined by a first alloying ratio of Ni 48 at.%; Al 0.1at.% and Be 51.9 at.%, the second one being defined by a second alloyingratio of Ni 50.1 at.%; Al 0.1 at.% and Be 49.8 at.%, the third one beingdefined by a third alloying ratio of Ni 61 at.%; Al 11 at.% and Be 28at.%, the fourth one being defined by a fourth alloying ratio of Ni 79at.%; Al 11 at.% and Be 10 at.%; the fifth one being defined by a fifthalloying ratio of Ni 71 at.%; Al 27 at.% and Be 2 at.% and the sixth onebeing defined by a sixth alloying ratio of Ni 48 at.%; Al 50 at.% and Be2 at.%.
 3. A heat resisting alloy consisting essentially of Ni, Al andBe, wherein the amounts thereof are defined by and included in apolygonal area on a triangular coordinate diagram of Ni, Al and Be, thepolygon having six apexes of which the first one being defined by afirst alloying ratio of Ni 51 at.%; Al 14 at.% and Be 35 at.%; thesecond one being defined by a second alloying ratio of Ni 69 at.%; Al 11at.% and Be 20 at.%, the third one being defined by a third alloyingratio of Ni 79 at.%; Al 11 at.% and Be 10 at.%, the fourth one beingdefined by a fourth alloying ratio of Ni 71 at.%; Al 27 at.% and Be 2at.%, the fifth one being defined by a fifth alloying ratio of Ni 48at.%; Al 50 at.% and Be 2 at.% and sixth one being defined by a sixthalloying ratio of Ni 48 at.%; Al 39 at.% and Be 13 at.%.